US4561521A - Variable assist power steering system - Google Patents

Variable assist power steering system Download PDF

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Publication number
US4561521A
US4561521A US06/678,844 US67884484A US4561521A US 4561521 A US4561521 A US 4561521A US 67884484 A US67884484 A US 67884484A US 4561521 A US4561521 A US 4561521A
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US
United States
Prior art keywords
valve
pressure
movable part
fluid flow
lands
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US06/678,844
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English (en)
Inventor
James J. Duffy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Visteon Global Technologies Inc
Original Assignee
Ford Motor Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ford Motor Co filed Critical Ford Motor Co
Priority to US06/678,844 priority Critical patent/US4561521A/en
Assigned to FORD MOTOR COMPANY, THE, DEARBORN, MI., A CORP. OF DE. reassignment FORD MOTOR COMPANY, THE, DEARBORN, MI., A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: DUFFY, JAMES J.
Priority to GB8527105A priority patent/GB2168016B/en
Priority to JP25462385A priority patent/JPH0678067B2/ja
Priority to DE19853542152 priority patent/DE3542152A1/de
Application granted granted Critical
Publication of US4561521A publication Critical patent/US4561521A/en
Assigned to VISTEON GLOBAL TECHNOLOGIES, INC. reassignment VISTEON GLOBAL TECHNOLOGIES, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FORD MOTOR COMPANY
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/02—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to vehicle speed
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87177—With bypass

Definitions

  • the steering gear mechanism shown in my co-pending application includes a rack-and-pinion power steering mechanism for a wheeled vehicle.
  • a power steering positive displacement pump is used in the steering system to supply working pressure to the fluid motor thus actuating the piston that drives the rack for the steering gear mechanism.
  • the power steering pump is engine driven. It is provided in known fashion with a constant flow control valve that permits a constant flow of fluid to the steering system regardless of pump speed.
  • the control valve for controlling distribution of pressure to the fluid motor for the steering system is a rotary valve comprising a valve sleeve connected to and movable with the pinion for the rack and pinion steering gear assembly.
  • An inner valve member received in the valve sleeve is provided with external valve lands that register with internal valve lands formed in the sleeve.
  • the inner valve member is connected to the torque input shaft, which is under the control of the vehicle operator.
  • the torque input shaft is connected also to the driving pinion for the rack-and-pinion assembly through a yieldable connection.
  • the connection is a torsion bar that is capable of deflecting to permit relative angular movement of the inner valve member with respect to the sleeve as steering torque is applied to the torque input shaft.
  • the valve structure is divided into two portions identified as a primary portion and a secondary portion. Each portion has its independent valve lands. Fluid is supplied from the pump to the primary portion, and the primary portion distributes pressure to one side of the fluid motor or the other depending upon the direction of the torque applied to the torque input shaft. A speed sensitive valve is used to control fluid flow from the outlet side of the pump to the secondary valve portion so that at high vehicle speeds a parallel flow path is provided between the steering valve and the pump as fluid is distributed to both steering valve portions.
  • the speed sensitive valve restricts the flow of fluid from the pump to the secondary valve section.
  • the primary valve section acts alone in the normal manner and the secondary valve portion is vented and not fed with fluid from the power steering pump.
  • the primary valve closes at about 2.5 degrees of relative valve motion of the inner valve with respect to the valve sleeve, and the torsion bar torque then is low.
  • the solenoid valve opens thereby allowing fluid to be distributed from the pump to the secondary valve portion in parallel with respect to the flow to the primary valve portion.
  • the secondary valve portion closes at about 5 degrees, providing a high torsion bar torque.
  • a change from a high degree of power assist to a low degree of power assist is effected by a variable force solenoid or an electric actuator motor which is used to establish a parallel flow path from the pump to the secondary valve sections through a variable flow orifice.
  • a speed sensing module controls the solenoid or actuator motor to open and close a variable orifice valve thus providing gradual changes in the degree of power assist as the vehicle speed changes.
  • FIG. 1 shows in schematic form a first embodiment of my invention including a dual rotary valve for a power steering gear together with a variable speed sensitive flow control orifice valve for controlling fluid flow from a power steering pump to each of two rotary valve portions.
  • FIG. 3 is a cross-sectional view of the dual rotary valve structure as seen from the plane of section line III--III of FIG. 1.
  • FIG. 4 is a chart that shows the relationship between the valve travel and the flow area for the power steering valve.
  • FIG. 5 is a chart that shows the relationship between torsion bar torque or valve degree travel and the pressure made available to the fluid motor.
  • FIG. 6 is a schematic cross-sectional view as seen from the planes of section lines III--III and VI--VI of FIG. 1 showing the relationship between the valve lands of the sleeve and the valve lands of the inner valve member at both the primary and secondary valve portions.
  • the geometry of the valve lands has been combined in a single view in FIG. 6 although in reality the actual plane of FIG. 6 is out of the plane of section lines III--III and VI--VI of FIG. 1.
  • FIG. 6 combines the information that would be viewed from the plane of section line III--III with the information that would be viewed from the plane of section line VI--VI.
  • FIG. 7 is a chart that shows the relationship between valve travel and total area for the valve seen in FIG. 6.
  • FIG. 8 is a chart that shows the relationship between torsion bar travel and pressure made available to the fluid motor for the steering gear that includes the valve schematically shown in FIG. 6.
  • FIG. 9 is a schematic cross-sectional view of an alternate form of orifice control valve for use in a system of the kind shown in FIG. 1.
  • FIG. 10 is a cross-sectional view of the valve of FIG. 9 as seen from the plane of section line X--X of FIG. 10.
  • numeral 10 designates a power steering pump for a vehicle power steering system having a vehicle engine and dirigible vehicle wheels.
  • the pump 10 is adapted to be driven by the vehicle engine. It includes a flow control valve of well-known design for maintaining a constant flow in an flow output passage 12 regardless of vehicle speed.
  • the flow return passage for the pump 10 is shown at 14.
  • a steering gear valve is shown generally at 16. It includes a valve housing 18 having a circular opening 20 which receives a valve sleeve 22. Positioned in the valve sleeve 22 is an inner valve 24. Valve 24 is provided with a primary valve section 26 and a secondary valve section 28. Valve section 26 includes valve lands 30 and valve section 28 includes valve lands 32. These lands 30 and 32 register with internal valve lands 34 and 36, respectively, formed in sleeve 22.
  • the sleeve 22 is ported at 38 to communicate with power steering pump supply passage 12. It is ported also at 40 to communicate with a secondary flow delivery passage 42.
  • a radial port 44 communicates with the registering primary valve lands 30 and 34 and a radial port 46 communicates with the secondary registering valve lands 32 and 36. Ports 44 and 46 are formed in the inner valve member 24.
  • the valve element 24 has a central opening 48 which receives torsion bar 50, the right hand end of which is pinned at 52 to an externally splined torque input shaft 54, the latter being connected to a driver controlled steering shaft.
  • the left hand end of the torsion bar 50 is pinned at 56 to a pinion 58 which is adapted to engage a steering gear rack that in turn is connected to the steering gear linkages for the dirigible wheels of the vehicle.
  • Pinion 58 is journalled by bushing 60 in the valve housing 18.
  • the central opening 48 communicates with space 62 which in turn communicates with flow return passage 14 through port 64 formed in the valve housing 18.
  • the valve sleeve 22 is connected to pinion 58 by means of a pin and slot connection defined by pin 66 received in slot 68 formed in the end of the sleeve 22.
  • Sleeve 22 thereby rotates with the pinion 58.
  • a fluid seal 70 isolates the pinion 58 and bushing 60 from the space 62.
  • Fluid seal 72 located at the opposite end of the inner valve member 24 seals the right hand end of the opening 20.
  • Valve member 24 is journalled in valve housing 18 at its right hand end by bearing 74.
  • a left turn port 76 in the valve sleeve 22 communicates with a left turn passage 78 that extends to one side of a fluid motor for the steering gear linkage.
  • a right turn port 80 communicates with a right turn passage 82 which communicates with the other end of the fluid motor.
  • a variable orifice valve 84 comprises a valve element 86 slidably positioned in the valve chamber 88 formed in a valve body.
  • Valve element 86 includes a valve stem 90 adapted to be engaged by a solenoid armature 92.
  • the armature 92 forms a part of a variable force solenoid 94 that has solenoid windings 96 that can be energized by an electronic speed sensing module 98 powered by the vehicle battery 100.
  • the solenoid includes a spring 102 that normally urges the valve element 86 into the position shown in FIG. 1, which is the opened position. Spring 102 overcomes the force of spring 104 acting in the opposite direction on the valve element 86.
  • Valve element 86 includes a tapered section 106 that registers with orifice 108 to provide a variable flow area for the fluid in passage 12. That area establishes a parallel flow path from the outlet side of the pump to the secondary feed passage 42.
  • the valve system of FIG. 1 provides a high degree of assist for parking and reduced assist for driving at high speeds.
  • the primary valve portion acts alone in the normal manner and the secondary valve is vented and not fed with fluid from the pump 10.
  • the primary valve portion closes at about 21/2° of valve travel for the inner valve with respect to the sleeve. Torsion bar torque is relatively low for such deflection.
  • the solenoid valve opens thereby providing a parallel flow delivery path through the passage 42. This effects an increased feel.
  • the secondary valve portion closes it flow port area upon relative deflection of about 5°. The torsion bar torque at that time is high.
  • a gradual increase in the degree of power assist is effected because orifice valve 84 progressively changes the flow area for passage 42 from a fully closed position to a fully opened position.
  • the degree of restriction is dependent upon the speed signal received from the electronic vehicle speed sensing module 98.
  • the lands 30 of the internal valve 24 are formed by four flats 108 which are machined by a transverse broaching operation. The flats 108 are broached transversely with respect to the axis of torsion bar 50 to develop a generally square primary valve section.
  • the internal valve lands 34 in the valve sleeve 22 register with the valve lands 30.
  • a separate land 30 registers with each internal valve land.
  • One internal valve land is formed by an axially extending groove in the sleeve which communicates with right turn passage 80.
  • Another internal valve land is formed by an axially extending groove that communicates with left turn passage 78.
  • the flow area for primary valve lands 30 and 34 is represented in FIG. 3 by the symbol A p . Since there are four valve lands in the sleeve, the total flow area for each land equals A p divided by 4.
  • the flow inlet ports for the primary valve are located 180° out of position, one with respect to the other. They both have been identified by common reference character 38. Each port 38 communicates with delivery passage 12 seen in FIG. 1.
  • FIG. 6 I have shown in a combined cross-sectional view the geometry of the primary valve section and the secondary valve section.
  • the secondary valve lands 32 on the inner valve 24 are formed by machining transverse flats 110. There are four such flats 110. They define a generally square valve cross section.
  • the lands 32 are slightly shorter than the lands 30 and thus the flow area defined by the registering internal lands 36 and the external lands 32 is not closed off until the torsion bar torque reaches a value that is higher than the torque that exists when the flow area defined by the lands 30 and 36 is closed off.
  • the primary valve lands close off the flow area when the relative displacement of the inner valve member relative to the sleeve equals 2.1°. This is seen by referring to FIG. 7.
  • the secondary valve lands do not close until the valve displacement reaches 4.1°.
  • the flow area for the primary valve lands and the secondary valve lands is represented in the curve of FIG. 7 by the line 112.
  • the flow area of the secondary valve lands after the primary valve lands close the primary valve flow area is represented by the straight line 114 in FIG. 7.
  • the relationship between the flow and the valve land areas illustrated in FIG. 7 develops a pressure torque relationship as indicated in FIG. 8.
  • the transition from the primary valve operating mode to the operating mode where both primary and secondary valves function is a progressive change depending upon the vehicle speed and the degree of fluid bypass from the power steering pump to the secondary valve feed passage 42 through the variable orifice valve 84.
  • the orifice valve progressively opens between the road speeds of 15 miles per hour to 55 miles per hour.
  • the orifice valve is fully opened at speeds in excess of 55 miles per hour.
  • valve element 114 of constant diameter. It has at one side thereof a variable orifice 116 which is adapted to register with port 118 located in secondary valve feed passage 42' which corresponds to passage 42 in the FIG. 1 embodiment. Valve element 114 is urged in a left hand direction by valve spring 120. Valve element 114 is slidably situated in valve bore 122. It includes a pressure balancing orifice 124 to equalize the pressure on either side of the valve element 114.
  • valve chamber on the left hand side of the valve element 114 communicates with passage 12' which corresponds to passage 12 in the FIG. 1 embodiment.
  • An electrical actuator motor 126 operates a worm screw 128 which engages valve element 114.
  • the screw 128 moves the valve element 114 in a left hand direction thereby restricting the degree of communication between orifice 116 and the port 118. Movement in the opposite direction occurs upon an increase in speed of the vehicle until full communication is established between passage 12' on the outlet side of the pump 10' and the port 118.
  • Electrical actuator motor 126 is under the control of an electronic module 130 which in turn is responsive to the signal received from a vehicle speed sensor 132.
  • a seal is provided at 134.
  • the primary valve lands as the internal diameter of the sleeve registers in sealing relationship with the external diameter of the inner valve member.
  • a fluid seal dam 136 which seals the primary lands from the secondary lands. Again this is accomplished by effecting a sealing relationship between the inside diameter of the sleeve with respect to the outside diameter of the inner valve member at a location intermediate the primary lands and the secondary lands.
  • the secondary valve lands have a wider metering valve opening than the primary valve side.
  • the secondary valve flow area closes at a higher angular deflection of the torsion bar than the deflection that exists when the primary valve land areas close.
  • FIG. 9 I have shown still another form of an orifice valve. It comprises a valve body 138 having a valve bore 140 which receives valve cylinder 142. Located in the cylinder 142 is a ball valve element 144 which is engaged by valve spring 146. Valve cylinder 142 is held in place by snap ring 148.
  • a flow inlet passage 12" supplies fluid from the power steering pump to the interior of the valve bore 140.
  • Passage 12" corresponds to passage 12 in the FIG. 1 embodiment.
  • Passage 12'" also communicates with the bore 140 thereby establishing a through passage from the pump 10 to the port 38 in the valve sleeve seen in FIG. 1.
  • Valve element 144 is adapted to register with valve land 150 defined by a valve cylinder 152 that is aligned with the ball 144 and the spring 146.
  • a plunger 154 is positioned slidably in the valve bore 152. Passage 42" communicates with the bore 152 on the left hand side of the plunger 154.
  • the plunger 154 can be moved within the bore 152 by a variable force solenoid 156.
  • the solenoid 156 is energized by a control module that is under the control of the vehicle speed sensor so that increasing vehicle speed causes an increase in the force of the solenoid when the vehicle speed increases the force opposing the spring 146 increases so that the effective area established by the valve element 144 and the valve land 150 increases.
  • the valve element 154 is pressurized on its right hand side by the pressure that exists in the passage 12" since the pressure in that passage is distributed through a cross-over passage 158 to the right hand side of the plunger 154.
  • the plunger 154 is pressure balanced and floats in the bore 152.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Steering Control In Accordance With Driving Conditions (AREA)
  • Power Steering Mechanism (AREA)
US06/678,844 1984-12-06 1984-12-06 Variable assist power steering system Expired - Lifetime US4561521A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US06/678,844 US4561521A (en) 1984-12-06 1984-12-06 Variable assist power steering system
GB8527105A GB2168016B (en) 1984-12-06 1985-11-04 Variable assist power steering system
JP25462385A JPH0678067B2 (ja) 1984-12-06 1985-11-13 液圧作動パワ−ステアリング装置
DE19853542152 DE3542152A1 (de) 1984-12-06 1985-11-28 Hydraulische hilfskraftlenkeinrichtung fuer kraftfahrzeuge

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/678,844 US4561521A (en) 1984-12-06 1984-12-06 Variable assist power steering system

Publications (1)

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US4561521A true US4561521A (en) 1985-12-31

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US06/678,844 Expired - Lifetime US4561521A (en) 1984-12-06 1984-12-06 Variable assist power steering system

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US (1) US4561521A (enrdf_load_stackoverflow)
JP (1) JPH0678067B2 (enrdf_load_stackoverflow)
DE (1) DE3542152A1 (enrdf_load_stackoverflow)
GB (1) GB2168016B (enrdf_load_stackoverflow)

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3729156A1 (de) * 1986-09-02 1988-03-10 Ford Werke Ag Variables hilfskraftsteuerungssystem unter verwendung elektronischer druckregelung
DE3733102A1 (de) * 1986-09-30 1988-04-07 Nissan Motor Variable servolenkung fuer ein fahrzeug
DE3744314A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
DE3744313A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
DE3744351A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Servolenkung mit variabler lenkkraftunterstuetzung
DE3744346A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
DE3744319A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
US4762302A (en) * 1985-06-03 1988-08-09 Jidosha Kiki Co., Ltd. Valve sleeve and method of manufacturing same
DE3821943A1 (de) * 1987-06-29 1989-01-19 Nissan Motor Variable servolenkeinrichtung
US4828067A (en) * 1987-10-30 1989-05-09 Ford Motor Company Electronic power assist control steering system
US4830131A (en) * 1987-01-30 1989-05-16 Nissan Motor Co., Ltd. Variable assist power steering system
US4844126A (en) * 1987-01-30 1989-07-04 Nissan Motor Co., Ltd. Rotary control valve for power assist steering system
US4846296A (en) * 1987-01-30 1989-07-11 Nissan Motor Co., Ltd. Hydraulic fluid pressure control system for use with power assist steering
US4852462A (en) * 1987-01-30 1989-08-01 Nissan Motor Co., Ltd. Operating noise-free fluid flow distributor circuit for variable assist power steering system
US4860635A (en) * 1986-05-12 1989-08-29 Nissan Motor Co., Ltd. Steering control valve for variable power assist steering system
US4877099A (en) * 1986-09-02 1989-10-31 Ford Motor Company Electronically controlled variable assist power steering system
US4926956A (en) * 1987-10-30 1990-05-22 Ford Motor Company Electronically controlled steering system
FR2645216A1 (fr) * 1989-03-31 1990-10-05 Bendix France Modulateur et circuit de direction assistee comprenant un tel modulateur
EP0401061A1 (fr) * 1989-05-31 1990-12-05 Alliedsignal Europe Services Techniques Modulateur et circuit de direction assistée comprenant un tel modulateur
US5029513A (en) * 1990-04-27 1991-07-09 Ford Motor Company Variable-orifice, servo-solenoid valve for a variable-assist power steering system
US5038878A (en) * 1988-10-28 1991-08-13 Nissan Motor Co., Ltd. Variable assist power steering apparatus
US5048630A (en) * 1990-04-09 1991-09-17 Ford Motor Company Power steering trim control system
DE4090852T (enrdf_load_stackoverflow) * 1989-05-22 1992-03-12
US5111660A (en) * 1991-03-11 1992-05-12 Ford Motor Company Parallel flow electronically variable orifice for variable assist power steering system
US5131486A (en) * 1989-12-18 1992-07-21 Trw Steering & Industrial Products Co., Ltd. (Japan) Power steering control valve mechanism
US5161959A (en) * 1991-03-11 1992-11-10 Ford Motor Company Viscosity sensitive hydraulic pump flow control
US5192196A (en) * 1991-03-11 1993-03-09 Ford Motor Company Flow control orifice for parallel flow fluid supply to power steering gear
US5297647A (en) * 1993-03-18 1994-03-29 Ford Motor Company Variable assist power steering gear with hydraulic reaction controls
US5307895A (en) * 1993-03-29 1994-05-03 Ford Motor Company Hydraulic reaction variable assist power steering control hydraulic "detent"
US5392875A (en) * 1991-12-23 1995-02-28 Ford Motor Company Hydraulic reaction variable assist power steering system
US5447209A (en) * 1993-02-26 1995-09-05 Koyo Seiko Co., Ltd. Hydraulic power steering device
US5782260A (en) * 1995-12-04 1998-07-21 Ford Global Technologies, Inc. Hydraulic flow priority valve
US5904222A (en) * 1996-11-06 1999-05-18 Ford Motor Company Variable assist power steering using vehicle speed and steering pressure
EP1149755A3 (en) * 2000-04-25 2003-08-20 Showa Corporation Hydraulic power steering apparatus for vehicle
US20090041605A1 (en) * 2007-07-13 2009-02-12 Schwabische Huttenwerke Automotive Gmbh & Co. Kg Adjusting valve for adjusting the delivery volume of a displacement pump
CN104057999A (zh) * 2013-02-13 2014-09-24 操纵技术Ip控股公司 具有磁性扭矩叠加的液压动力转向系统

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
US4570736A (en) * 1985-01-07 1986-02-18 Ford Motor Company Dual flow variable assist power steering gear mechanism
JPS61247575A (ja) * 1985-04-25 1986-11-04 Toyoda Mach Works Ltd 動力舵取装置の操舵力制御装置
GB2272191B (en) * 1992-10-23 1996-01-31 Adwest Eng Ltd Fluid control system for a vehicle power steering mechanism

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GB2130989B (en) * 1982-05-19 1986-01-22 Ford Motor Co Speed sensitive power steering system

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US4063490A (en) * 1974-09-13 1977-12-20 Ford Motor Company Rack and pinion power steering gear mechanism
US4189024A (en) * 1978-06-23 1980-02-19 Zahnradfabrik Friedrichshafen Ag Auxiliary power steering for motor vehicles
US4186818A (en) * 1978-07-11 1980-02-05 Zahnradfabrik Friedrichshafen Ag Auxiliary power steering for motor vehicles
US4434866A (en) * 1982-05-19 1984-03-06 Ford Motor Company Speed-sensitive power steering system

Cited By (52)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4762302A (en) * 1985-06-03 1988-08-09 Jidosha Kiki Co., Ltd. Valve sleeve and method of manufacturing same
US4860635A (en) * 1986-05-12 1989-08-29 Nissan Motor Co., Ltd. Steering control valve for variable power assist steering system
US4760892A (en) * 1986-09-02 1988-08-02 Ford Motor Company Variable assist power steering system using electronic pressure control
DE3729156A1 (de) * 1986-09-02 1988-03-10 Ford Werke Ag Variables hilfskraftsteuerungssystem unter verwendung elektronischer druckregelung
US4877099A (en) * 1986-09-02 1989-10-31 Ford Motor Company Electronically controlled variable assist power steering system
DE3733102A1 (de) * 1986-09-30 1988-04-07 Nissan Motor Variable servolenkung fuer ein fahrzeug
US4771841A (en) * 1986-09-30 1988-09-20 Nissan Motor Co., Ltd. Variable power assist steering system for vehicle
US4860846A (en) * 1986-12-27 1989-08-29 Nissan Motor Co., Ltd. Vehicle speed responsive variable assist power steering system
DE3744351A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Servolenkung mit variabler lenkkraftunterstuetzung
DE3744346A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
DE3744314A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
US4958695A (en) * 1986-12-27 1990-09-25 Nissan Motor Company, Limited Variable assist power steering system
DE3744319A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
US4884648A (en) * 1986-12-27 1989-12-05 Nissan Motor Company, Limited Variable assist power steering system with varying power assist characteristic
DE3744313A1 (de) * 1986-12-27 1988-07-07 Nissan Motor Variables servolenksystem
US4865147A (en) * 1986-12-27 1989-09-12 Nissan Motor Company, Limited Hydraulic fluid circuit for variable assist power steering system
US4862985A (en) * 1986-12-27 1989-09-05 Nissan Motor Co., Ltd. Variable assist power steering system with varying power assist with vehicle speed
US4830131A (en) * 1987-01-30 1989-05-16 Nissan Motor Co., Ltd. Variable assist power steering system
US4852462A (en) * 1987-01-30 1989-08-01 Nissan Motor Co., Ltd. Operating noise-free fluid flow distributor circuit for variable assist power steering system
US4846296A (en) * 1987-01-30 1989-07-11 Nissan Motor Co., Ltd. Hydraulic fluid pressure control system for use with power assist steering
US4844126A (en) * 1987-01-30 1989-07-04 Nissan Motor Co., Ltd. Rotary control valve for power assist steering system
US4875542A (en) * 1987-06-29 1989-10-24 Nissan Motor Co., Ltd. Hydraulic system for variable assist power steering system
DE3821943A1 (de) * 1987-06-29 1989-01-19 Nissan Motor Variable servolenkeinrichtung
DE3835774A1 (de) * 1987-10-30 1989-05-18 Ford Werke Ag Hydraulische hilfskraftlenkeinrichtung fuer kraftfahrzeuge
US4926956A (en) * 1987-10-30 1990-05-22 Ford Motor Company Electronically controlled steering system
US4828067A (en) * 1987-10-30 1989-05-09 Ford Motor Company Electronic power assist control steering system
US5038878A (en) * 1988-10-28 1991-08-13 Nissan Motor Co., Ltd. Variable assist power steering apparatus
FR2645216A1 (fr) * 1989-03-31 1990-10-05 Bendix France Modulateur et circuit de direction assistee comprenant un tel modulateur
EP0396433A1 (fr) * 1989-03-31 1990-11-07 Alliedsignal Europe Services Techniques Modulateur et circuit de direction assistée comprenant un tel modulateur
US5058697A (en) * 1989-03-31 1991-10-22 Bendix Europe Services Techniques Modulator and power-assisted steering circuit containing such a modulator
DE4090852C2 (de) * 1989-05-22 2003-07-31 Kayaba Industry Co Ltd Servolenkung
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Also Published As

Publication number Publication date
GB2168016B (en) 1988-01-20
JPH0678067B2 (ja) 1994-10-05
DE3542152A1 (de) 1986-06-12
GB8527105D0 (en) 1985-12-11
JPS61139563A (ja) 1986-06-26
DE3542152C2 (enrdf_load_stackoverflow) 1991-01-31
GB2168016A (en) 1986-06-11

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